my bobcat doesn't want to move, its jerky. first start it and it seems to move but after couple minutes it sounds like its getting air bound. hyd tank shows level is correct. i took the filler cap off but didn't help. i replaced the hyd oil filter due to my light coming on. fixed the low pressure light. so is there some where that maybe i can check or bleed the air off. I've raised the bucket up and down but you can feel there is air in it, haven't ran this machine much but l when i pulled it in the shed it was fine. help me out here fellows. don't have a lot of knowledge on this 743b bobcat. thanks
when my fluid got low (damn leak) this 743 squealed like a pig, herky jerky boom and bucket...but it still drove fine. after adding oil it took a few days to get the foamed air bubbles out of the system. However like i said...it seemed to drive fine.
Don't know if it's related but I think a 743(B) uses a double U-joint to connect the pump to the engine. Have heard that if the drive or control levers get jerky the first thing to check is that the 2 U-joints are greased. These are often neglected because they are harder to get at. Some machines the U-joints aren't greaseable. Would have to check your manual. Major PIA to have to replace the U-joints. I don't have a Bobcat but have a double U-joint. I grease them every time I change the oil.
well i started it up this morning . did run better. got all the air out of the hyd rams now. i did notice my sight glass was all foamed up. i will check on the u joint. i think mine has that . i didnt know if there was some where i could bleed it off or just have to let it bleed itself. thanks to you both.
Sitting overnight or longer should help get rid of some of the air in the oil as long as there are no suction leaks.
There are 3 grease fittings on the driveshaft. Lift the cab, flashlight and a mirror on a stick to see what yer dealing with. Easiest with 2 people, one watches the mirror, other rotates the engine with a wrench, get the fittings at about 45°. Then lay on yer tummy and reach in with the grease hose, helper works the gun. Need at least a 30" long hose. Inspect with mirror to make sure the grease went in the zerks.....wash, rinse, repeat. Ed
if there is air in the system, one thing that may help is to jack it up and block it securely with all wheels off the ground. then run it forward for a while and then reverse for a while to help purge the air. that way there is no load on the hydrostatic system.
i did see in the manual mine does have it, now i got to find it
i thought about that. when i had it up on blocks with wheels off it worked fine.
how long did you run it with the wheels off the ground? 2- 5 minutes in each direction should be enough to purge any air
i ran it today and it seems to work pretty good until it warms up and gets alittle jery. when i shut it off i noticed the sight glass is real foamy so im going to drain the tank and put new oil in it and see if that helps. thanks
Something is causing the foaming. Do you know what type of oil is in it now?
Could be sucking air somewhere between the tank and the charge pump. No suction filter on this model?